TPS65911: Crystall circuit

Chambin Zhang

Prodigy 165 points

Part Number: TPS65911

Hello,

Can the crystal 32.768kHz run without capacitors?

Thanks.

over 1 year ago

0 Matt Sunna over 1 year ago

TI__Guru* 81034 points

Hi,

Capacitors are required by the crystal specifications. This thread may be helpful: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/1319838/tps65911-crystal-oscillator-design

Best regards,

Matt

0 Chambin Zhang over 1 year ago in reply to Matt Sunna

Prodigy 165 points

Hi Matt,

Could you tell me the "Load crystal oscillator (COSCIN, COSCOUT)" TPS65911 datasheet mentioned equal to 22pF(C11,C10) + parasitic PCB capacitor?

if parasitic PCB capacitance is 1pF, the Load crystal oscillator will be 23pF?

Thanks.

0 Field Tolson over 1 year ago in reply to Chambin Zhang

TI__Genius 10772 points

Hi Chambin,

I believe this should be correct, however it may be easier to use an even number. You can see an example on page 121 in the typical application section which contains a schematic and components. Here you can see OSC32KIN and OSC32KOUT have 12pF capacitors.

Thanks,
Field

0 Chambin Zhang over 1 year ago in reply to Field Tolson

Prodigy 165 points

Hi Field,

Do you have idea to test 32.768KHz crystal accuracy? we have a issue about clock time deviation over 20ppm at 25C work condition.

Thanks

0 Matt Sunna over 1 year ago in reply to Chambin Zhang

TI__Guru* 81034 points

Hi Chambin,

Sorry, I do not know of an easy way to test the crystal accuracy. You may want to reach out to the crystal supplier for this question.

Best regards,

Matt

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TPS65911: Crystall circuit